1. Field of the Invention
The present invention relates to a method of operating a cutting wheel arrangement for a suction dredge and an arrangement for carrying out the method.
2. Description of the Prior Art
German Patent 3,015,452 shows and describes a bucket wheel for a suction dredge. The bucket wheel is mounted so as to be rotatable about a horizontal axis and has excavating buckets provided uniformly spaced apart on the outer circumference of its bucket wheel body. Each bucket wheel is U-shaped as seen in radial cross-section of the bucket wheel. The free bucket ends are connected to the bucket wheel body and each have an inlet opening facing forwardly in the direction of rotation of the bucket wheel. This inlet opening is greater than its outlet opening. The bucket wheel defines an opening on the outer circumference extending over the entire length thereof between the sides of the U-shape of the excavating buckets. Adjacent this opening is located the suction mouth of a suction line extending through a stationary side wall of the bucket wheel into the interior of the bucket wheel. The suction mouth has on its upper edge an extension which extends at an angle directed against the direction of rotation of the bucket wheel through this opening and into the outlet openings of the excavating buckets.
The outer end of this extension is located on the same level as the axis of rotation of the bucket wheel. In the radial cross-section, the excavating buckets may have an essentially rectangular or trapezoidal shape, while in the tangential cross-section they may also have a trapezoidal shape.
German Offenlegungsschrift 2,907,485 describes and shows a bucket wheel having a flat, cylindrical body with at least one, partially open side surface. The cylindrical peripheral plane thereof has openings which lead into the buckets which are connected to the bucket wheel and are provided with cutting teeth. The shaft of the bucket wheel is supported by bearings which are located at a forked outer end of the bucket flight of the excavator boom. The shaft may be driven through a gear wheel by means of a hydraulic motor.
The main portion of the cylindrical body includes a box-like suction device which has an open side in the form of a circular arc defining a suction opening and extends near the inner surface of the cylindrical peripheral plane of the main portion of the bucket wheel body. The box-like suction device is mounted by means of a flange connection to a fastening device which is held by the shaft of the bucket wheel. An adjusting device including a piston and a cylinder is rotatably connected on one of its ends to the bucket flight and at its other end to the fastening device, so that the box-like suction device can be swung by means of the adjusting device.
On a side of the suction device is provided an opening which is connected to a pipe bend. The other end of the pipe bend is connected to a flexible pipe which, in turn, is connected to a suction pipe by means of another pipe bend.
U.S. Pat. No. 4,058,914 discloses a suction dredge of a suction head of special construction connected to a suction pipe. The suction head is composed of a tee whose central portion is connected to the suction pipe, while the two side pieces have fastening flanges. A cutting device is provided on each fastening flange. The cutting device includes a tubular portion in which is mounted a drive motor. Each drive motor is connected to a cutting wheel which has outwardly projecting knives arranged in a circle, wherein the planes of the knives are inclined conically. The cutting device additionally includes a helically-shaped component from which the cutting knives project outwardly.
In the T-shaped manifold to which the two outwardly projecting cutting devices are fastened are pivotally mounted a pipe flap, the pivot axis of the flap extending perpendicularly to the connecting piece of the T-shaped manifold.
The flap opens at its forward end in a slide member which, in its first position, closes the connecting opening of one suction pipe and, in the second position, closes the suction opening of the other suction pipe. The flap may be adjusted by means of an adjusting device on board the ship.
German Auslegeschrift 2,305,859 shows and describes a cutting suction head with a pair of cutting disks mounted on the ends of a driven shaft. Each cutting disk has a plurality of essentially strip-shaped cutting blades. The cutting blades are arranged on the circumference of the cutting disk and extend in radial and axial direction. A suction pipe with its suction opening extends between the cutting disks. The suction pipe is arranged above the driven shaft. A guide plate is provided between the cutting blades of the pair of cutting disks. The guide plate extends from its fastening point at the suction opening along the circumference of the cutting disks to the vicinity of the bottom side of the cutting head. The cutting disks rotate in direction of the suction opening.
The above-described arrangement has the disadvantage that the material to be removed by suction is conveyed against the force of gravity into the suction pipe opening provided above the drive shaft. This disadvantage results in a reduced volumetric efficiency of the suction pipe.
It is the primary object of the present invention to provide a cutting wheel arrangement for a suction dredge of the aforementioned type which ensures that the material cut by the cutting stirrups or blades is removed with a high volumetric efficiency.